1. Field of the Invention
The present invention relates to a light source apparatus that is suitable for an endoscope.
2. Description of the Related Art
Conventionally, endoscopes configured so that an elongated endoscope is inserted into, e.g., a body cavity to perform observation of a site to be examined and/or various treatments have widely been used. In such endoscopes, a light source apparatus for shooting an image of the inside of a cavity is employed. In recent years, a light source apparatus employing semiconductor light sources such as LEDs as light emission sections has been sometimes used. Such light source apparatus can perform light adjustment control of the LEDs by means of PWM control in which duty ratios of respective drive pulses are varied and/or current control in which LED currents are varied.
Examples of such light source apparatus using LED light sources include an apparatus disclosed in International Publication No. WO2012/108420 (hereinafter referred to as Literature 1). The apparatus in Literature 1 employs a combination of a white LED and a violet LED, enabling normal observation (white light imaging: WLI) using white light illumination and special light observation such as narrow-band observation (narrow band imaging: NBI) using violet light illumination.